Unwrapping apparatus and method for unwrapping articles

ABSTRACT

An unwrapping apparatus, configured to unwrap a stack of wrapped articles, including an unwrapper head, which includes a housing, a cutter head, a drive, wherein the drive is configured to rotate the cutter head relative to the housing. The cutter head includes a gripper, a knife, and an actuator, configured to move the gripper along a path of movement relative to the housing, between a retracted position and an advanced position. The unwrapping apparatus further including a robotic manipulator arm, configured to move the unwrapper head, a registration device, configured to register a contour of the stack, and a controller, configured to control the robotic manipulator arm and the drive, in accordance with the registered contour.

The present invention relates to an apparatus for unwrapping articles, such as palletized packages, by cutting the wraps around the articles, and to a method for autonomous unwrapping of articles.

Palletized articles are often wrapped with a flexible plastic wrap, in order to keep the articles from moving or even falling off the pallet, during transportation.

The wrap is usually applied to the articles about a vertical axis being orthogonal to the plane of the pallet.

In some situations, when for instance it is desired to keep the articles dry, it is further necessary to apply the wrap to the articles about a horizontal axis being parallel to the plane of the pallet.

The articles are unwrapped either manually using knifes, or an unwrapping apparatus.

Today, unwrapping apparatuses often use suction to pull a part of the wrap and subsequently pierce or cut the part of the wrap being pulled, using a knife or a pointed object.

EP 0625465 discloses an unwrapping apparatus, for removing the wrap from palletized articles, comprising suction cups for applying suction to a part of the wrap and for pulling that portion, a pointed object for piercing the part of the wrap being pulled, and removing devices, for removing the severed wrap.

However, articles are not always stacked in a way to form a cuboid on the pallet, but are sometimes stacked randomly, or forming a shape having a contour which forms steps.

The above mentioned EP document is only adapted to unwrap articles, that form a cuboid. It is not adapted to unwrap palletized articles, that are stacked in a way forming steps, or in a random way. It is further only adapted to initiate the unwrapping process on the sides of the articles, and not at the top for instance, and only when suction is applied.

Yet another problem with the prior art is, that an operator is required to operate the unwrapping apparatus, or to set the pathways for the wrap removing device(s) to follow the contour of the wrap, such that the unwrapping apparatus does not cut into the articles.

U.S. Pat. No. 5,463,841 discloses an unwrapping apparatus which is adapted to remove wraps from the top of palletized articles. It is however limited to only remove the wraps from articles on pallets of a certain size and height due to its construction, occupies much space due to its size, and is immobile.

The object of the present invention is inter alia to provide an unwrapping apparatus and a method for unwrapping palletized wrapped articles, which solves the above mentioned problems, and overcomes the above mentioned limitations.

SUMMARY

In view of this object, an unwrapping apparatus, configured to unwrap a stack of wrapped articles is provided, comprising an unwrapper head, which comprises a housing, a cutter head, a drive, the drive being configured to rotate the cutter head relative to the housing, the cutter head comprising a gripper, a knife, and a first actuator, being configured to move the gripper along a first path of movement relative to the housing, between a first retracted position and a first advanced position, a robotic manipulator arm, configured to move the unwrapper head, a registration device, configured to register a contour of the stack, and a controller, configured to control the robotic manipulator arm and the drive, in accordance with the registered contour, and the controller further being configured to control the first actuator.

In this way, a registration device will register a contour of the stacked articles, and sending the information to the controller, which then will calculate/establish a cutting path through the wrap, along the contour of the stack of articles. The cutting path preferably extends in a vertical plane, from the top of the stack to the bottom of the stack.

The controller then controls the robotic manipulator arm to move the unwrapper head along the cutting path, while the gripper is moved to the advanced position such as to get under a free edge of the wrap and drag the wrap towards an edge of the article, and then guide the wrap towards the knife while being moved along the surface of the articles, without damaging the stacked articles.

In another embodiment of the unwrapping apparatus, the unwrapper head further comprises a second actuator, configured to move the gripper and knife along a second path of movement, between a second retracted position and a second advanced position, the first path of movement and the second path of movement not being parallel, and wherein the controller further controls the second actuator, and a suction channel having a suction inlet at the knife, wherein the second retracted position is closer to the suction channel than the second advanced position.

In this way, the unwrapping apparatus can be used to start cutting on any surface of the stacked articles. The unwrapper head will use suction at a suction inlet of the unwrapper head to pull a part of the wrap towards the knife which is retracted towards a retracted position, in order not to damage the wrap, until the controller controls the second actuator to move the knife to an advanced position, thereby piercing the part of the wrap being pulled, thereby allowing the gripper to get below a now free end of the damaged wrap, and drag the wrap towards an edge of the article, or simply guide the wrap towards the knife. The unwrapping may for instance begin at a vertical surface of a stacked article, or at a horizontal surface of an article, which is wrapped on a top surface and therefore has no free edge to be grabbed by the gripper.

In another embodiment, the first actuator and the gripper are linked to each other by a pivoting lever, the first actuator acting on one end of the pivoting lever and the gripper is arranged on another end of the pivoting lever.

In this way, the first actuator can move the gripper between a retracted position, which is desirable in a situation, where a measurement is to be conducted and an advanced gripper would provide an obstacle, and prevent a precise measurement, and an advanced position, which is desirable when for instance a free end of a wrap is to be gripped.

In one embodiment, the gripper can only be fully retracted to the second retracted position by the second actuator, when the gripper is retracted towards the first retracted position by the first actuator. In this way, the gripper will not collide with a wall of the suction inlet when being retracted towards the second retracted position by the second actuator.

In another embodiment, the unwrapper head further comprises a spring, configured to bias the gripper towards the first advanced position, and wherein the first actuator is configured to counteract the spring and move the gripper towards the first retracted position, when activated.

Pressing the gripper towards the first advanced position using a spring, allows the gripper to follow the contour of the stack of articles while being advanced, thereby being able to catch a free end of the wrap, and drag it towards an edge of the article, and stay under the uncut wrap while following the contour, and guiding the uncut wrap portions towards the knife, being arranged at a top portion of the gripper, but arranged further within the suction channel than the gripper, in order only to cut the portion of wrap that is guided towards it by the gripper, and not cut into the surface of the articles.

In another embodiment, the registration device comprises one of the following: a camera or scanner, or a device for registering the rotation of wheels arranged on the unwrapper head, or a device for registering the force resisting the movement of the robotic manipulator arm, or sensors configured to detect distances, or a combination of two or more of the above mentioned registering options.

In this way, a contour of the stacked articles can either be registered by taking a picture of the contour, or scan the contour and get a digital representation of it, or registering the distances that the wheels travelled along the surfaces of the stacked articles thereby getting measurements of the lengths of the surfaces of the articles, or getting measurements of the lengths by registering where and when the unwrapper head moved by the robotic manipulator arm has reached a surface or an edge of the stack of articles, or measuring distances and using sensors, or using a combination of two or more of the above mentioned techniques, to register the contour of the stacked articles. The information will then be sent to the controller, which will calculate and determine a cutting path, based on the information obtained by the registering device, and control the robotic manipulator arm to move the unwrapper head, based on the determined cutting path.

In the case where the registration device comprises a camera or a scanner, the registration device will be configured to obtain, capture, record, or scan an image of a contour of the stack, and send a digital representation of the image to the controller, which then will process and/or analyse that digital representation and determine a cutting path. The processing and/or analysis of the digital representation of the image may be conducted by the camera or scanner, which then will determine a cutting path, and send information about the cutting path to the controller.

In view of the above mentioned object, a method for unwrapping a stack of wrapped articles using an unwrapping apparatus is provided, using an unwrapping apparatus with an unwrapper head comprising:

a) a wrapping gripper, such as i) a wrapping gripper comprising an arm with a free end for wrapping gripping or ii) a wrapping gripper with suction inlets for gripping the wrapping by applying suction to the wrapping, optionally rotatably mounted to a housing of the unwrapper head, and

b) a knife, the unwrapping apparatus further comprising:

a robotic manipulator arm, configured to move the unwrapper head,

a registration device, configured to register a contour of the stack,

a controller, configured to control the robotic manipulator arm,

the method comprising the steps of:

registering the contour of the stack using the registration device, establishing a cutting path which follows said registered contour of stack, and

moving the unwrapper head to a top surface portion of the stack, and gripping by the gripper a free end edge of the wrapping of the stack at the top surface portion, such as by applying suction by the gripper to the wrapping at the free end edge, and dragging by the gripper the free end edge of the wrap towards an edge of the top surface portion, and cutting the wrap along the cutting path by moving the unwrapper head. The established cutting path preferably extends in a vertical plane, and preferably from the top of the stack to the bottom of the stack.

In this way, a registration device will register a contour of the stacked articles, and send the information to the controller, which then will calculate/establish a cutting path, along the contour of the stack of articles. The controller then controls the robotic manipulator arm to move the unwrapper head along the cutting path, while the gripper is moved to the advanced position such as to get under a free edge of the wrap and drag the wrap towards an edge of the article, and then guide the wrap towards the knife while being moved along the cutter head, without damaging the stacked articles.

In another embodiment, the method of the registering of a contour of the stack by the registering device, comprises one of the following steps:

-   -   recording one or more images using a camera or a scanner, or     -   counting the number of rotations of wheels arranged on the         unwrapper head during the moving of the cutter head along the         contour, or     -   using sensors sensing during the moving of the cutter head along         the contour the presence of obstacles or measuring distances, or     -   measuring during the moving of the cutter head along the contour         loads resisting the movement of the robotic manipulator arm, or     -   a combination of two or more of the above mentioned steps.

In another embodiment, the registering of a contour of the stack by the registering device, comprises the steps of:

-   -   moving the unwrapper head in a horizontal direction towards a         portion of the stack of wrapped articles until a force is         measured resisting a further movement of the unwrapper head in         the horizontal direction or an obstacle is detected using         sensors, and         -   moving the unwrapper head in a vertical direction, until             either             -   1 an edge is detected by registering the absence of a                 force resisting a further movement in the vertical                 direction, or using sensors detecting the absence of an                 obstacle, or             -   2 a corner is detected by measuring the presence of a                 force resisting a further movement in the vertical                 direction, or using sensors detecting the presence of an                 obstacle, and         -   moving the unwrapper head in a horizontal direction, and         -   repeating the above mentioned steps, until a free end of the             wrap is detected, and         -   sending location information of the change in directions of             movements of the unwrapper head and the location of the free             end of the wrap from the registering device to the             controller, while conducting the above mentioned steps of             registering the contour of the stack.

In this way, measurements of the lengths of the surfaces of the stack are obtained, by registering where and when the unwrapper head, moved by the robotic manipulator arm, has reached a surface or an edge of the stack of articles, and thereby needs to change the direction of movement, in order to continue following the contour of the stack.

In another embodiment, the method comprises the steps of:

-   -   using a spring to bias the gripper towards a first advanced         position relative to a housing comprising the cutter head along         a first path of movement,     -   using a first actuator to apply a load on one end of a lever         connecting the first actuator with the gripper to counteract the         pressing force of the spring and moving the gripper towards a         first retracted position along the first path of movement.

In this way, the gripper will be in an advanced position, thereby following the contour of the stack of articles, while being retractable towards a retracted position, when the first actuator is activated. Retracting the gripper is desired when for instance a process of registering the contour of the stack of articles is conducted, and it is desired that the gripper is not in an advanced position in order to not become an obstacle hindering an accurate acquisition of information.

In another embodiment, the method comprises the step of moving the gripper and knife between a second retracted position and a second advanced position along a second path of movement using a second actuator, wherein the first and second path of movement not being parallel.

In this way, the second actuator is able to retract the gripper and the knife towards a second retracted position, in a direction away from the suction inlet. This is desired, when for instance the unwrapping process is to be started on a vertical surface of the stack of wrapped articles, or on a top surface of the stack without the presence of a free end of the wrap. A portion of the wrap is pulled towards the suction inlet. If the gripper is not retracted, it will make an obstacle preventing the portion of the wrap from being pulled properly into the suction chamber of the cutter head, and if the knife is not retracted, the pulled portion of the wrap would immediately be pierced. This may not be desired. Therefore, the gripper and the knife are retractable using the second actuator, towards a second retracted position along a second path of movement, being further inside the suction chamber. This will further allow the portion of pierced wrap to be pulled towards the suction chamber along the second path of movement, and allow the gripper to be moved towards the first advanced position, along the first path of movement, and eventually get under the wrap, since the first path of movement and the second path of movement not being parallel.

In another embodiment, the method comprises the steps of:

-   -   arranging the unwrapper head at a surface of the wrap, and     -   retracting the gripper towards the first retracting position,         and     -   pulling a portion of the wrap, using suction, towards a suction,         inlet of a suction channel comprised in the unwrapper head, and     -   piercing the portion of wrap being pulled towards the suction         inlet using the knife arranged at the suction inlet.

In view of the above mentioned object, another method for unwrapping a stack of wrapped articles using an unwrapping apparatus as described in the previously mentioned embodiments, is provided, the method comprising the steps of:

-   -   determining a cutting path which follows the registered contour         of the stack, and     -   moving the cutter head to a top surface portion of the stack,         and     -   gripping a free end edge of the wrapping of the stack at the top         surface portion, and     -   dragging the free end edge of the wrap towards an edge of the         top surface portion, and     -   initiating a cutting of the wrap along the cutting path while         dragging uncut portions of the wrap downwards along the         determined cutting path.

In this way, a registration device will register a contour of the stacked articles, and sending the information to the controller, which then will calculate a cutting path through the wrap, along the contour of the stack of articles. The controller then controls the robotic manipulator arm to move the unwrapper head along the calculated cutting path, while the gripper is moved to the advanced position such as to get under a free edge of the wrap and drag the wrap towards an edge of the article, and then guide the wrap towards the knife while being moved along the cutter head, without damaging the stacked articles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a stack of wrapped articles on a pallet and an unwrapper head of the apparatus of the invention, placed on top of the stack.

FIG. 2 is a view of a front portion of the unwrapper head.

FIG. 3 is a view of the unwrapper head.

FIG. 4 is a schematic cross-sectional view of the unwrapper head.

FIG. 5 is a schematic cross-sectional side view of the unwrapper head showing the gripper fully retracted in a first retracted position.

FIG. 6 is a schematic cross-sectional side view of the unwrapper head showing the gripper fully advanced in a first advanced position.

FIG. 7 is a schematic side view of the unwrapper head, showing the cutter head dragging a wrap by its top edge, along the top side of a wrapped article, towards the edge of the article.

FIG. 8 is a schematic side view of the unwrapper head shown in FIG. 7 , having reached the edge of the wrapped article.

FIG. 9 a is a schematic side view of the unwrapper head shown in FIG. 7 , while removing the wrap at a corner, defined by two stacked articles.

FIG. 9 b is a schematic side view of the unwrapper head shown in FIG. 7 , while removing the wrap along a corner of a stacked article.

FIG. 10 a is a schematic side view of the unwrapper head shown in FIG. 7 , showing a portion of the wrap on a top side of a wrapped article, being pulled towards the cutter head, using suction.

FIG. 10 b is a schematic side view of the unwrapper head shown in FIG. 10 a , while piercing through the portion of the wrap being pulled, using a knife.

FIG. 10 c is a schematic side view of the unwrapper head shown in FIG. 10 b , while cutting the wrap along a top side of the wrapped article.

FIGS. 11 a-11 d show an alternative embodiment of the unwrapper head, in perspective and cross-sectional view, and in a first position cutting at the top of a stack and in a second position cutting along the side of a stack, respectively.

DETAILED DESCRIPTION

An embodiment of the invention will now be explained in more detail below by reference to the figures.

FIG. 1 shows the unwrapper head 1, positioned on top of a stack S of wrapped articles 50, 50′, arranged on a pallet 60. The wrap 40 wrapping the stack S of articles 50, 50′ is indicated by shaded lines.

FIG. 2 shows a closer view of a part of the unwrapper head 1, comprising a housing 2, the housing 2 comprising wheels 3 and a cutter head 10, the cutter head 10 comprising: a gripper 11 having in the shown embodiment an arm 11 a with a free end defining a gripping tip 11 b, a knife 12, and a suction inlet 13 in communication with a suction channel 14. The shown gripper 11 is spring loaded using a spring (not shown). The knife 12 is arranged at a top portion of the gripper 11, and arranged closer to the suction channel 14 than the gripper 11.

FIG. 3 shows the unwrapper head 1 comprising a drive 4, which may be a motor, preferably a gear motor, preferably mounted to the housing 2. The drive 4 is configured to rotate the cutter head 10, in order to allow the cutter head 10 to adapt to any surface of an article 50 to be unwrapped.

FIG. 4 shows a first actuator 15, in connection with the gripper 11, configured to move the gripper 11 along a first path of movement FP between a first retracted position (FIG. 5 ) and a first advanced position (FIG. 6 ).

For clarity reasons, the first path of movement FP is in the figures shown parallel to the gripper 11. However, the first path of movement FP also follows a longitudinal axis of the gripper 11 or is also aligned with the direction of movement of the gripper 11.

FIG. 4 further shows a second actuator 16, which is in connection with both the gripper 11 and the knife 12, and is configured to simultaneously move the gripper 11 and the knife 12 in the same direction along a second path of movement SP between a second retracted position (FIG. 10 a ) and a second advanced position (FIG. 10 b ), wherein the second advanced position is closer to a suction inlet 13 than the second retracted position is.

For clarity reasons, the second path of movement SP is in the figures shown parallel to the cutter head 10. However, the second path of movement SP also follows a longitudinal axis of the cutter head 10 or is also aligned with the direction of movement of the knife 12, which also is the direction of movement/action of the second actuator 16.

As shown in FIGS. 4-6 , the connection between the second actuator 16 and the gripper 11 and knife 12 may be a direct connection, whereas the connection between the first actuator 15 and the gripper 11 may have a link in-between, such as a mechanism comprising a pivoting lever 18, acting as a tilt, wherein the first actuator 15 acts on one side of the pivoting lever 18, and the gripper 11 is arranged on the other side of the pivoting lever 18. A spring (not shown) will keep the gripper 11 in tension, biasing it into the first advanced position, until the first actuator 15 counteracts the spring force, and acts on one side of the pivoting lever 18, thereby moving the gripper 11, which is arranged on the other side of the pivoting lever 18, towards the first retracted position. When the first actuator 15 is deactivated, the spring load will move the gripper 11 towards the first advanced position, and keep pressing on the gripper 11 to keep it in that position. This situation is seen in FIG. 6 .

It is further seen, that the first path of movement FP brought about by the first actuator 15, and the second path of movement SP brought about by the second actuator 16, are not parallel.

The unwrapping apparatus further comprises a controller C and a robotic manipulator arm 5, controlled by the controller C and configured to move the unwrapper head 1 along the top surfaces and side surfaces of the stack S of articles.

The controller C further controls the first and second actuators 15, 16, the drive 4, and the suction.

When fully advanced by the first actuator 15, the tip part 11 b of the gripper 11 is reaching beyond the foremost front end of the cutter head 10 as seen in FIG. 6 , while the gripper 11 when fully retracted, is arranged as seen in FIG. 5 .

The gripper 11, when fully advanced by the second actuator 16, is positioned at a foremost front end of the cutter head 10 and in front of the suction inlet 13, as seen in all figures other than FIG. 10 a , whereas when the gripper 11 is fully retracted by the second actuator, the tip part 11 b of the gripper 11 is positioned within the suction chamber 14, as seen in FIG. 10 a.

The figure further shows holes in the rear end of the housing 2, for mounting of the robotic manipulator arm 5.

FIG. 5 shows schematically a cross-sectional side view of the unwrapper head 1 shown in FIG. 3 , wherein the gripper 11 is fully retracted. In this situation, the first actuator 15 acts on the pivoting lever 18 to counteract the spring, and force the gripper 11 into a fully retracted position.

FIG. 6 shows schematically a cross-sectional side view of the unwrapper head 1, in a situation, where the first actuator 15 no longer acts on the pivoting lever 18, and the spring therefore has forced the gripper 11 into the advanced position.

As shown in FIGS. 5 and 6 , when the gripper 11 is in the first and second advanced positions, the gripper 11 may touch a surface of an article, while when in the first retracted position, the gripper 11 will not be suitable to touch a surface of an article.

To describe the unwrapping method, an example of a process is made, using reference to the figures. Reference is made again to FIG. 1 .

A scanning process is initiated prior to a cutting process, whereby a cutting path is determined which follows a vertical contour of the stacked articles 50, 50′, using sensors arranged on the unwrapper head 1 or the resisting forces measured resisting the further movement of the robotic manipulator arm 5. This is to ensure a fully automatic cutting process without cutting into the stacked articles 50, 50′.

When a stack of wrapped articles 50, 50′ as seen in FIG. 1 is to be unwrapped, the unwrapper head 1 is brought to the bottom of the wrapped articles 50, 50′ or the pallet 60, using the robotic manipulator arm 5.

At this point, the gripper 11 and the knife 12, are fully retracted in both first and second retracted positions, and the cutter head 10 is pushed towards the vertical side of the lowest article 50 or towards the pallet 60.

The robotic manipulator will begin moving the unwrapper head 1 upwards along the vertical contour of the stack S of articles 50, 50′, while pushing the cutter head 10 against the sides of the articles 50, 50′, but without damaging the articles 50, 50′. The wheels 3 of the housing 2 reduce the friction between the unwrapper head 1 and the wrap wrapping the articles.

The registering device will record the vertical and horizontal contour of the stack S of articles 50, 50′ during the entire movement of the unwrapper head 1, using the sensors mounted to the unwrapper head 1 or using the registered resisting forces, until the unwrapper head 1 reaches the top edge of the highest article 50 of the stack S of articles 50, 50′, and sending the registered information to the controller C, which determines a cutting path based on these information.

Thus, the controller C will let the unwrapper head 1 travel upwards along the vertical side of an article 50, until it detects an edge of that article. From that point, the controller C will let the unwrapper head 1 travel horizontally along the horizontal top side of the article 50, until it detects a vertical side of an article 50′, wherefrom it again lets the unwrapper head 1 travel upwards along the vertical side of the article 50′.

Once the top of the stack S of articles has been reached, the controller C will move the unwrapper head 1 horizontally on top of the stack S of articles, until an edge 41 of the wrap 40 has been detected. This situation is depicted in FIG. 7 .

Reference is now made to FIG. 7 . At this point, the controller C deactivates the first actuator 15 in order to allow the spring to force the gripper 11 towards a first advanced position, and controls the second actuator 16 to bring the gripper 11 and the knife 12 towards a second advanced position, as seen in FIG. 7 .

As seen in FIG. 7 , the gripper 11 will travel towards the first advanced position, until the top side surface of an article 50 is reached. From here, the controller C will control the robotic manipulator arm 5 to move the unwrapper head 1 backwards along the previously scanned pathway. The gripper 11 will eventually grip an edge 41 of the wrap 40, and drag that free end edge 41 of the wrap 40 towards an edge of the top surface portion of the article, as seen in FIGS. 7-8 .

When the unwrapper head 1 reaches the edge of the article 50, and continues following the pathway vertically downwards, as seen in FIG. 8 , the knife 12 which is put in the second advanced position, will eventually press against a portion of the wrap 40 beginning with the dragged edge 41 of the wrap 40, and eventually cut that portion, beginning with the edge 41 of the wrap 40. The cutting process of the unwrapping process has thus begun.

FIG. 9 a shows schematically a situation, where the unwrapper head 1 has reached a corner defined between two articles 50, 50′. The drive 4 has rotated the cutter head 10 relative to the housing 2, such that the cutting of the wrap 40 continues, following the cutting path along the horizontal surface of the article 50 below. In this situation it is seen, that the gripper 11, due to the tension from the spring load, still functions as a guide, guiding the wrap 40 towards the knife 12.

FIG. 9 b shows schematically a similar situation as in FIG. 9 a , but where the unwrapper head 10 has to follow a part of the contour of the stack S defining a cavity, and the drive 4 therefore has rotated the cutter head 10 to form an appropriate angle with the housing 2.

FIG. 10 a shows a situation where the unwrapping begins on top of an article, where no wrap edge 41 is present. This may be a situation, where the top surface of the article or stack S is wrapped. However, the same process would apply when the unwrapping is to begin on a vertical side surface of an article 50.

In this situation, the drive 4 has rotated the cutter head 10 into an appropriate vertical position. In a situation where the unwrapping begins on a vertical side surface of an article 50, the drive 4 would rotate the cutter head 10 into a horizontal position.

In this situation, the suction is activated, thereby pulling a part of the wrap 40 towards the suction inlet 13 at the front end of the cutter head 10, keeping that particular part of the wrap 40 under tension. The gripper 11 and the knife 12 are seen retracted in the second path of movement SP, such as not to damage the part of the wrap 40 being pulled. The gripper 11 is in this situation retracted in the horizontal (first path of movement FP) and the vertical (second path of movement SP) direction by both the first and second actuators 15, 16, respectively.

As schematically illustrated in FIG. 10 b , the second actuator 16 then moves the knife 12 and the gripper 11 into the second advanced position in the vertical direction along the second path of direction, thereby piercing the part of the wrap 40 held under tension. The gripper 11 is however still retracted in the horizontal direction by the first actuator 15.

The wrap 40 may also be pierced by simply retracting the gripper 11 towards the second retracting position, while the knife 12 is in the second advanced position, as seen in FIG. 10 b , wherein when suction is activated, a portion of the wrap 40 will be pulled towards the knife 12, and thereby be pierced.

During the two alternative situations mentioned above, the suction is still activated, and the severed part of the wrap 40 is pulled towards the suction inlet 13. This in turn allows the gripper 11 to get below a part of the wrap 40 near the newly created free end edge 41 of the wrap 40.

From here, the unwrapping process arrives at a situation similar to that illustrated in FIG. 7 , where suction no longer is necessary, and where the gripper 11 drags the edge 41 of the wrap 40 towards an edge of the article, where after the cutting process may begin. This situation is schematically illustrated in FIG. 10 c.

FIG. 10 c further schematically shows the gripper 11 having been put into the first advanced position in the horizontal direction by the first actuator 15, in order to improve the process of guiding the wrap 40 towards the knife 12.

FIGS. 11 a-11 d show an alternative unwrapper head 1′ with an alternative type of gripper 11′, rotatably mounted to a housing 2′ of the unwrapper head 1′, by which gripper 11′ the wrap 40 is gripped at its free end edge 41 by applying suction to the wrap 40 via suction inlets 13′ defining the alternative gripper 11′ that does not have the arm 11 a with the gripping tip 11 b discussed above, wherein the applied suction pulls the wrapping 40 away from the wrapped articles 50, 50′ towards one or more knives 12′ mounted to the unwrapper head 1′ in the vicinity of the one or more suction inlets 13′, such as between the suction inlets 13′ of a pair of such suction inlets 13′. The alternative gripper 11′ preferably is controlled to rotate relative to the housing 2′ from a position wherein the suction inlets 13′ face downwards towards horizontal portions of the wrap 40, as shown in FIG. 11 c , such as at the top of the stack of wrapped articles 50, 50′, and the unwrapper head 1′ has wheels 3′ bearing against the side of the stack of wrapped articles (as the unwrapper head 1′ is in one embodiment initially moved upwards for the registration of the contour), during the cutting along the sides by the knives 12′. 

1. An unwrapping apparatus, configured to unwrap a stack of wrapped articles, comprising: an unwrapper head comprising: a housing; a cutter head; a drive, wherein said drive is configured to rotate said cutter head relative to said housing; wherein said cutter head comprises: a wrapping gripper; a knife; and an actuator configured to move said wrapping gripper along a path of movement relative to said housing between a retracted position and an advanced position; a robotic manipulator arm configured to move said unwrapper head; a registration device configured to register a contour of said stack; and a controller configured to control said robotic manipulator arm and said drive in accordance with said contour, and said controller further being configured to control said actuator.
 2. The unwrapping apparatus according to claim 1, wherein said unwrapper head further comprises: a second actuator configured to move said gripper and said knife along a second path of movement relative to said housing between a second retracted position and a second advanced position, wherein said path of movement and said second path of movement are not parallel to one another, and wherein said controller further controls said second actuator; and a suction channel having a suction inlet at said knife, wherein said second retracted position is closer to said suction channel than said second advanced position.
 3. The unwrapping apparatus according to claim 1, wherein said actuator and said wrapping gripper are linked to each other by a pivoting lever, and wherein said actuator acts on one end of said pivoting lever and said wrapping gripper is arranged on another end of said pivoting lever.
 4. The unwrapping apparatus according to claim 1, wherein said unwrapper head comprises a spring configured to bias said wrapper gripper towards said advanced position, and wherein said actuator is configured to counteract said spring and move said wrapper gripper towards said retracted position, when activated.
 5. The unwrapping apparatus according to claim 1, wherein said registration device comprises one of the following: a camera, a scanner, or a device for registering rotation of wheels arranged on said unwrapper heady; or a device for registering a force resisting movement of said robotic manipulator arm; or sensors configured to detect distances; or a combination of two or more of the above mentioned registering options.
 6. A method for unwrapping a stack of articles with a wrapping using an unwrapping apparatus, said unwrapping apparatus comprising: an unwrapper head comprising: a wrapping gripper selected from the group consisting of: i) a wrapping gripper comprising an arm with a free end for wrapping gripping; and ii) a wrapping gripper with suction inlets for gripping a wrapping by applying suction to said wrapping; and a knife; wherein said unwrapping apparatus further comprises: a robotic manipulator arm, configured to move said unwrapper heady, a registration device configured to register a contour of said stack; and a controller, configured to control said robotic manipulator arm, said method comprising: registering said contour of said stack using said registration device; determining a cutting path which follows said contour of said stack; and moving said unwrapper head to a top surface portion of said stack; gripping by said wrapping gripper a free end edge of said wrapping of said stack at said top surface portion; dragging by said wrapping gripper said free end edge of said wrap towards an edge of said top surface portion; and cutting said wrapping along said cutting path by moving said unwrapper head.
 7. The method according to claim 6, wherein said registering of said contour of said stack by said registering device, comprises one of the following processes: recording one or more images using a camera or a scanner; or counting a number of rotations of wheels arranged on said unwrapper head and contacting said stack during movement of said cutter head to said top surface portion; or using sensors sensing, during movement of said unwrapper head along said contour, a presence of obstacles or measuring distance; or measuring, during said moving of said unwrapper head to said top surface portion, loads resisting movement of said robotic manipulator arm; or a combination of two or more of the above mentioned processes.
 8. The method according to claim 6, wherein said registering of said contour of said stack by said registering device, comprises: moving said unwrapper head in a horizontal direction towards a portion of said stack of articles until a force is measured resisting a further movement of said unwrapper head in said horizontal direction or an obstacle is detected using sensors; moving said unwrapper head in a vertical direction, until either: 1) an edge is detected by registering an absence of a force resisting a further movement in said vertical direction, or using sensors detecting an absence of an obstacle; or 2) a corner is detected by measuring a presence of a force resisting a further movement in said vertical direction, or using sensors detecting a presence of an obstacle; and moving said unwrapper head in said horizontal direction; repeating the above mentioned processes until a free end edge of said wrapping is detected; and sending location information of change in directions of movements of said unwrapper head and a location of said free end edge of said wrapping from said registering device to said controller, while conducting the above mentioned processes of registering said contour of said stack.
 9. The method according to claim 6, wherein the method comprises: using a spring to bias said wrapping gripper towards an advanced position relative to a housing comprising said unwrapper head along a path of movement; and using an actuator to apply a load on one end of a lever connecting said actuator with said wrapping gripper to counteract a pressing force of said spring and moving said wrapping gripper towards a first retracted position along said path of movement.
 10. The method according to claim 9, comprising moving said wrapping gripper and said knife between a second retracted position and a second advanced position along a second path of movement using a second actuator, wherein said first path and said second path of movement are not parallel to one another.
 11. The method according to claim 9 comprising: arranging said unwrapper head at a surface of said wrapping; retracting said wrapping gripper towards said retracted position; pulling a portion of said wrapping, using suction, towards a suction inlet of a suction channel comprised in said unwrapper head; and piercing said portion of said wrapping being pulled towards said suction inlet using said knife arranged at said suction inlet.
 12. A method for unwrapping a stack of wrapped articles using an unwrapping apparatus comprising: an unwrapper head comprising: a housing; a cutter head; a drive, wherein said drive is configured to rotate said cutter head relative to said housing; wherein said cutter head comprises: a wrapping gripper; a knife; and an actuator configured to move said wrapping gripper along a path of movement relative to said housing between a retracted position and an advanced position; a robotic manipulator arm configured to move said unwrapper head; a registration device configured to register a contour of said stack; and a controller configured to control said robotic manipulator arm and said drive in accordance with said contour, and said controller further being configured to control said actuator; said method comprising: registering said contour of said stack using said registration device; determining a cutting path which follows said contour of said stack; moving said cutter head to a top surface portion of said stack; gripping, by said wrapping gripper, a free end edge of a wrapping of said stack at said top surface portion; dragging, by said wrapping gripper, said free end edge of said wrapping towards an edge of said top surface portion; and initiating a cutting of said wrapping along said cutting path while dragging uncut portions of said wrapping downwards along said cutting path.
 13. The unwrapping apparatus according to claim 1, wherein said wrapping gripper is in the form of an arm with a free end defining a gripping tip.
 14. The method according to claim 6, wherein said wrapping gripper with suction inlets is rotatably mounted to a housing of said unwrapper head.
 15. The method according to claim 6, wherein said gripping by said wrapping gripper a free end edge of said wrapping of said stack at said top surface portion is performed by applying suction by said wrapping gripper to said wrapping at said free end edge. 